MWCNT – PMMA as Thin Films

INTRODUCTION
Polymer have universally been applied in many of the devices as insulation material and optoelectronic uses. This has been brought about by their unique nature, such as the high malleability, its light weight and ability to be contrived at low temperatures and at low rates. CNt are worthy of several varied uses, such as the gas sensors [1], electro-magnetic shielding [2], and electro-static discharges [3]. Such composites are usually produced by the help of using a range of the strategies, as follows: (a) CNT functionalization, (b) mixing strategies variation (melt, solution), (c) changing the mixing ratio of the CNT to the matrix, (d) changing the matrices or (e) changing CNT characteristics [4]. CNTs as such tend to be chosen due to their exceptional properties, including: thermal, electrical, optical and mechanical. However, the challenge to use the CNTs as the reinforcements in the composites is connected to the fact, that they do not disperse and that they tend to agglomerate due to the tough inter-molecular Vander Waals and high characteristic ratio [5].
Consequently, the CNT/Polymer nanocomposite is the possible kind of nanomaterials with the perspective applications, namely the light emitting diodes (LED) , photovoltaic cells, and transport layers. The matrix polymer in this current work has been chosen, namely, the MMA due to its applicability to a wide range of production and processing methods and its non-crystalline nature (by which we would be deprived of the many difficulties encountered in dealing with the crystallization properties) accused of saintess, with his saintly spectacles [6].

MATERIALS AND METHODS
Preparation of PMMA/MWCNTs Thin films 
Spin coated films of the PMMA/CNTs of the various concentrations are equipped. The material that has been used in the extant article is the polymethyl methacrylate, the PMMA solution were prepared by adding 26 mg of PMMA to 1ml of chloroform and put on the magnetic stirrer to mix it well after 30 s multi-walled carbon nanotube (MWCNTs) were added at varying rate (1%,3%,5). Lastly, thin films are spin coated at rotation speed of 3000rpm and rotation time of 10sec , layers were dehydrated at 60o C.

RESULTS AND DISCUSSION 
Optical properties 
Enhanced PMMA transmittance spectra at the wave-length range of 200nm 1000nm have also been determined using a diversity of concentration levels. Figs. 1 and 2 shows spectra of the absorption and transmittance of different gradations of the MWCNT concentration. It was revealed that that all the sections have been nearly clear in UV till the region of NIR. As the concentration is enhanced so the transparency of the sample is enhanced. That is why, it has been justified that all of the samples possess PMMA main characteristic which is high in transparency.
Optical band gap for the PMMA thin film when in differences in concentration with MWCNTs the UV-Vis spectra of PMMA/MWCNTs nanocomposite thin films have been also measured with the objective to determine the optical band gap depending on the result of the UV-Vis measurement through the plot (h implies alpha h nu poly)2 as against hυ of PMMA/MWCNTs nanocomposite. The value of optical band gap increased with the addition of MWCNTs into PMMA can be varied to (3.8-3.5) eV. The result indicates that the 0 wt% MWCNTs produces the 3.8eV and 1 wt%, 5 wt% MWCNTs results in the decreasing value. band gap of the all samples is tabulated in (1) and schemed in Fig. 3.
It has been observed that the Eg has decreased with the upsurge of the concentration of the PMMA. The optical scattering of grain boundaries may be the cause of variations in optical band gap at different transport of different concentrations of the PMMA the reduction in the values of the light absorption as show in table 1 [7]. Generated in the thin film prepared at 30 mg might be owing to deficiencies in the films that have increased as the development beside the c-axis has decreased at the high concentrations. It has been considered that the eternal-effect of the grain boundaries that scatter light is minimized. Those values have been conflicting to those of that are 4.6eV [8, 9]. 
Fig. 4 demonstrates the shift of the optical conductivity on the deposit of the electrons in the range of the wave-lengths, where maximum conductivity in the range of the ultraviolet radiation, and decreasing of its value with the increase of the values of the wave-lengths, Using the graph, it will be predictable that rising the amount of the MWCNTs material, the optical connectivity of the nanocomposites will be fluctuating not only between the pure PMMA and the pure MWCNTs when these materials are brought together. The MWCNTs and PMMA were successfully bonded in series where by drastic rise in the Optical Connectivity is observed when the MWCNTs is more than 2.0 wt.%. [11]
The refractive index (𝑛) for all samples before and after being doped in Fig. 5, will we seen that the 𝑛and 𝑘 values increase with accumulative the doping of MWCNTs [11].
Similar behaviors relate to the density of absorbing centers like layers absorption, singularity in excitation transition and other defects in the crystal lattice and are dependent on the conditions of the sample preparation. The values of the dielectric constant increases as the wavelength also increases and the doping level of MW-CNTs. At the wavelength of 400 nm the corresponding values of the dielectric constant at 0, 1, 3, and 5 % MW-CNTs contents were 4,5,6 and7, respectively, and 0.000045, 0.000223, 0.000377and 0.000442, respectively, at the imaginary part (Figs. 6 and 7). In addition, this gain due to the variation of 𝜀1 chiefly relies on 𝑛2 for the reason that of small values of 𝑘2 while 𝜀2 which is proportionate to 𝑘value which is associated to the dissimilarity of absorption coefficients [13].

Surface Morphology of thin films MWCNTS -PMMA
 In line with the inquest into PMMA concentration effect on morphology, the surface topography of the films has been determined by following an AFM method as depicted in Fig. 8. The FS images demonstrated that all films are uniform with no deferent substantial limits across all the concentrations. The RA with MW-CNTS 0.75nm, 0.8nm, 10.11 nm and 7.47nm when 0,1, 3, and 5 percent added. The outcomes have demonstrated that the concentration of RA has been raised in increase of concentration [14]. The viscosity of such a solution with increase in concentration of PMMA also leads to such an increase in surface roughness.

CONCLUSION
Our experiments examined shows MWCNTs are impacting optical properties of PMMA through the technique of spin coating technique. It is depicted that the electrical conductivity is enhanced three orders of magnitudes when the MWCNTs are incorporated. This is supposed to be because of the creation of conducting ways on the polymer. As the content of MWCNTs on the ratio of 3wt.% to 5 wt.% are added the conductivity rises drastically as well. Hence, it can be said that the conductivity will rise with additions of higher content of MWCNTs. The optical band gap exhibits results that depict a downward trend in optical band gap values, except the two samples (3 wt.% and 5wt.%). This could be due to the absence of dispersion of MWCNTs in PMMA.

CONFLICT OF INTEREST
The authors declare that there is no conflict of interests regarding the publication of this manuscript.